Oscillating timing unit electro-magnetic drive



Nov. 9, 1965 R. FAVRE 3,217,191

OSCILLATING TIMING UNIT ELECTROMAGNETIC DRIVE Filed Jan. 15, 1965 United States Patent 3,217,191 OSCILLATIN G TIMING UNIT ELECTRO- MAGNETIC DRIVE Robert Favre, 36 Servan, Lausanne, Switzerland Filed Jan. 15, 1965, Ser. No. 425,874 4 Claims. (Cl. 310-66) The present invention is a continuation-in-part of US. application Ser. No. 196,814, now Patent 3,173,036.

It relates to oscillatory systems, particularly for electrical time-measuring devices, which consist of a mechanical oscillator, together with an electro-magnetic device driving the oscillator, with at least one active element, preferably an electronic amplifier, there being arranged, in the control circuit of the amplifier, at least one control coil, and, in the output circuit of the amplifier, at least one operating coil.

Such oscillatory systems, serving as the time basis for a clock or watch, are already known, wherein the oscillator may consist of a balance-wheel, a tuning fork, a piezoelectric oscillator, or even a torsion oscillator. Oscillators executing torsional oscillations operate at frequencies between about and 150 cycles, and thus embrace a medium range of frequencies, lying between that of a balance-wheel and that of a piezo-electric oscillator.

The present invention relates to those systems in which the movable element of the oscillator carries at least one permanent magnet cooperating with a stationary coil (or coils).

One problem to be solved in such oscillatory systems is to provide a good electro-ma-gnetic interaction between the oscillating magnet and the coil, and a good magnetic path for eliminating magnetic leaks.

This problem is solved by the present invention.

More precisely, the present invention relates to an oscillating system for an electrical time-measuring device comprising, a mechanical oscillator capable of executing oscillations, said mechanical oscillator comprising at least an oscillating element, an electro-magnetic device for oscillatably driving said element comprising an electronic amplifier, whose input circuit comprises at least one control coil and whose output circuit comprises at least one driving coil, at least one permanent magnet fixed to said oscillating element and co-operating with at least one of said coils, said oscillating element having at least a recess open on one side and a soft-iron core fixed thereto with its axis perpendicular to the oscillating axis of said element and located in the plane of oscillation and surrounded by a stationary coil belonging to the corresponding one of said coils, said permanent magnet being located in said recess outside this core and with its axis perpendicular to the coil axis, one pole-face of said magnet facing the external surface of said stationary coil, and each soft-iron core and the corresponding permanent magnet being freely movable relatively to the corresponding sta tionary coil during the oscillation of the oscillating element.

Two forms of embodiment of the system according to the present invention will be fully disclosed hereafter, reference being made to the accompanying drawing, in which:

FIG. 1 is the top plan view of a first embodiment, in which only the oscillator and the coils fixed on the baseplate of a watch are shown, the mechanical oscillator oscillating in a plane parallel to said base-plate.

FIG. 2 is an electrical diagram corresponding to FIG. 1, and

FIG. 3 is a second form of embodiment, only slightly different from that of FIG. 1.

In FIG. 1., on the base-plate of a time-measuring device, there is a torsion spring 2 of cruciform cross section, on

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the upper portion of which is arranged an oscillating arm Said arm 33 is parallel to the base-plate 1 and is provided with two heads 34, 34' located at its two ends. Said heads 34 and 34 are antisymmetric, which ensures a good equilibrium.

The head 34 (respectively 34') which is in the form of a parallelepiped and encloses a cavity 39 (respectively 39) of the arm 33 suspended from the torsion spring 2, carries on the one hand a soft-iron core 36 (respectively 36') and also a cylindrical permanent magnet 35 (respectively 35'). While the axis of the soft-iron core 36 (respectively 36) is perpendicular to the longitudinal axis of the arm and is located in the plane of oscillation, the magnetic axis of the permanent magnet 35 (respectively 35') which is secured to the internal wall surface of the outer end of the arm, is oriented perpendicularly to the axis of the soft-iron core. A coil 37 (respectively 37') secured to the base-plate by means of an angle piece 38 (respectively 38) surrounds the soft-iron core 36 (respectively 36), one pole-face of the magnet 35 (respectively 35) being directed on to the outside of the coil 37 (respectively 37) and having a cylindrical shape adapted to the likewise cylindrical shape of the coil, so that this pole-face and the external wall surface of the coil, face one another at only a very small distance apart.

The distances between the individual elements are so dimensioned that during the oscillation of the arm 33, the soft-iron core 36 (respectively 36) can plunge freely into the coil, and the permanent magnet 35 (respectively 35') can move freely along the external coil surfaces.

The coils 37 and 37' are shown in FIG. 2, 37 being the operating coil and 37 the control coil in series with a condenser C; reference numerals 14 and C designate a transistor and a battery, respectively; and R is a resistor.

During the oscillation, transistor 14 is conducting when an impulse induced in coil 37 by magnet 35 is produced, and provides a driving impulse through the operating coil 37. The latter interacts with magnet 35 to entertain the oscillations of arm 33.

In order to produce the greatest possible changes of magnetic flux during the oscillation, and therefore the greatest possible coil currents, the diameters of magnets 35 and 35' are made substantially greater than the diameters of iron-cores 36 and 36, respectively.

The present invention is not, of course, restricted to the above form of embodiment, and various changes of detail can be made therein without going beyond its scope. In particular, as shown in FIG. 3, magnets 35 and 35' can be surrounded by sleeves 4t) and 40' respectively, of high density non-magnetic material, which permits to in crease the moment of inertia of the arm 33, without increasing the dimensions of the latter.

The oscillating system according to the invention can also comprise two arms oscillating on a common baseplate, resiliently connected to said base-plate, or two oscillating arms located at both ends of one common spring and resiliently fixed to the base-p1ate, by their middle portion.

Also, both coils and cores can be mounted on the same side of the arm.

What is claimed is:

1. An oscillating system for an electrical time-measuring device comprising, a mechanical oscillator capable of executing oscillations, said mechanical oscillator comprising at least an oscillating element, an electro-magnetic device for oscillatably driving said element comprising an electronic amplifier, whose input circuit comprises at least one control coil and whose output circuit comprises at least one driving coil, at least one permanent magnet fixed to said oscillating element and co-operating with at least one of said coils, said oscillating element having at least a recess open on one side and a soft-iron core fixed thereto with its axis perpendicular to the oscillating axis of said element and located in the plane of oscillation and surrounded by a stationary coil belonging to the corresponding one of said coils, said permanent magnet being located in said recess outside this coil and with its axis perpendicular to the coil axis, one pole-face of said magnet facing the external surface of said stationary coil, and each soft-iron core and the corresponding permanent magnet being freely movable relatively to the corresponding stationary coil during the oscillation of the oscillating element.

2. An oscillating system for an electrical time-measuring device comprising, a mechanical oscillator capable of executing oscillations, said mechanical oscillator comprising at least an oscillating element, an electro-ma-gnetic device for oscillatably driving said element comprising an electronic amplifier, whose input circuit comprises at least one control coil and whose output circuit comprises at least one driving coil, at least one permanent magnet fixed to said oscillating element and co-operating with at least one of said coils, a sleeve of high density nonmagnetic material surrounding each of the magnets, whereby the moment of inertia of said oscillating element is increased, said oscillating element having at least a recess open on one side and a soft-iron core fixed thereto with its axis perpendicular to the oscillating axis of said element and located in the plane of oscillation and surrounded by a stationary coil belonging to the corresponding one of said coils, said permanent magnet being located in said recess outside this core and with its axis perpendicular to the coil axis, one pole-face of said magnet facing the external surface of said stationary coil, and each soft-iron core and the corresponding permanent magnet being freely movable relatively to the corresponding sta- 4t tionary coil during the oscillation of the oscillating element.

3. An oscillating system according to claim 1, in which the diameter of each permanent magnet is substantially greater than that of the corresponding soft-iron core.

4. An oscillating system for an electrical time-measuring device comprising a mechanical oscillator capable of executing oscillations, said mechanical oscillator comprising at least an oscillating element, an electro-magnetic device for oscillatably driving said element comprising an electronic amplifier, whose input circuit comprises at least one control coil and whose output circuit comprises at least one driving coil, two permanent magnets fixed to said oscillating element and co-operating each with at least one of said coils, said oscillating element having, at each end thereof, a recess open on one side and a softiron core fixed thereto with its axis perpendicular to the oscillating axis of said element and located in the plane of oscillation and surrounded by a stationary coil belonging to the corresponding one of said coils, each of said two permanent magnets being located in the corresponding recess outside the corresponding core and with its axis perpendicular to the coil axis, one pole-face of said magnet facing the external surface of said stationary coil, and each soft-iron core and the corresponding permanent magnet being freely movable relatively to the corresponding stationary coil during the oscillation of the oscillating element, the orientation of the recess and of the coil at one end of the oscillating element being directed relatively to the orientation of the recess and coil at the other end of the oscillating element, whereby said oscillating element as a whole is symmetrical about its axis of oscillation.

No references cited.

ORIS L. RADER, Primary Examiner. 

1. AN OSCILLATING SYSTEM FOR AN ELECTRICAL TIME-MEASURING DEVICE COMPRISING, A MECHANICAL OSCILLATOR CAPABLE OF EXECUTING OSCILLATIONS, SAID MECHANICAL OSCILLATOR COMPRISING AT LEAST AN OSCILLATING ELEMENT, AN ELECTRO-MAGNETIC DEVICE FOR OSCILLATABLY DRIVING SAID ELEMENT COMPRISING AN ELECTRONIC AMPLIFIER, WHOSE INPUT CIRCUIT COMPRISES AT LEAST ONE CONTROL COIL AND WHOSE OUTPUT CIRCUIT COMPRISES AT LEAST ONE DRIVING COIL, AT LEAST ONE PERMANENT MAGNET FIXED TO SAID OSCILLATING ELEMENT AND CO-OPERATING WITH AT LEAST ONE OF SAID COILS, SAID OSCILLATING ELEMENT HAVING AT LEAST A RECESS OPEN ON ONE SIDE AND A SOFT-IRON CORE FIXED THERETO WITH ITS AXIS PERPENDICULAR TO THE OSCILLATING AND OF SAID ELEMENT AND LOCATED IN THE PLANE OF OSCILLATION AND SURROUNDED BY A STATIONARY COIL BELONGING TO THE CORRESPONDING ONE OF SAID COILS, SAID PERMANENT MAGNET BEING 